The invention relates to a MEMS microphone, specifically to packaging for a MEMS microphone that improves performance of the microphone.
MEMS microphones include a MEMS processed die, a substrate for making electrical input/output connections, and a separate housing with an acoustically perforated lid which structurally and electrically protects the die and bond wire connections. In some devices, an application specific integrated circuit (ASIC) is included on the same die as the MEMS. Generally, a large volume of air exists between the exterior of the housing and the active face of the MEMS die (i.e., a transducer). This volume of air causes a Helmholtz impedance/resonance which distorts the motion of the transducer of the microphone and, especially at high frequencies, the output of the microphone.